EP0160331B1 - Abstimmanordnung - Google Patents
Abstimmanordnung Download PDFInfo
- Publication number
- EP0160331B1 EP0160331B1 EP85200507A EP85200507A EP0160331B1 EP 0160331 B1 EP0160331 B1 EP 0160331B1 EP 85200507 A EP85200507 A EP 85200507A EP 85200507 A EP85200507 A EP 85200507A EP 0160331 B1 EP0160331 B1 EP 0160331B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- tuning
- circuit
- frequency
- resonant
- arrangement
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 239000003990 capacitor Substances 0.000 claims abstract description 41
- 230000008878 coupling Effects 0.000 description 7
- 238000010168 coupling process Methods 0.000 description 7
- 238000005859 coupling reaction Methods 0.000 description 7
- 230000007423 decrease Effects 0.000 description 6
- 230000003247 decreasing effect Effects 0.000 description 5
- 230000000694 effects Effects 0.000 description 3
- 230000001419 dependent effect Effects 0.000 description 2
- 230000001603 reducing effect Effects 0.000 description 2
- 230000001939 inductive effect Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000001172 regenerating effect Effects 0.000 description 1
- 230000009131 signaling function Effects 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
- H03J3/00—Continuous tuning
- H03J3/28—Continuous tuning of more than one resonant circuit simultaneously, the tuning frequencies of the circuits having a substantially constant difference throughout the tuning range
Definitions
- the invention relates to a tuning arrangement comprising a tunable RF-circuit, a mixer stage coupled thereto, and an oscillator circuit having a tunable resonant circuit, which oscillator circuit is coupled to the mixer stage, each circuit being tuned to a respective resonant frequency by a common tuning voltage, wherein at least the circuit having the higher resonant frequency comprises a parallel arrangement of on the one hand a circuit inductance and on the other hand a series arrangement of a tuning capacitor and a padding capacitor.
- the two circuits are tuned with the aid of mutually equal, variable capacitance diodes to which the same tuning voltage is applied from the common tuning voltage input, the tuning frequency of the oscillator resonant circuit being higher than the tuning frequency of the RF-circuit, so that a variation in the tuning voltage results in a variation in the tuning frequency, which is greater for the oscillator resonant circuit than for the RF-circuit.
- This tuning-voltage dependent variation of the tuning frequency-alternatively referred to as the tuning slope ⁇ of the oscillator-resonant circuit is reduced by means of the padding capacitor.
- the frequency-dependent deviation of the difference between the tuning frequencies of the two circuits is indeed reduced, but an appropriate parallel variation in these tuning frequencies is only achieved in a limited portion of the tuning range: particularly at lower tuning frequencies, said difference was found to decrease with frequency to an unwanted high degree.
- the padding capacitor can be switched to a lower capacitance value, for example by switching a circuit capacitance in parallel with it.
- the invention has for its object to provide a tuning arrangement in which a substantially constant frequency distance between the tuning frequencies of the two circuits is maintained over at least a larger portion of the tuning range than is possible in the prior art tuning arrangement without switching the padding capacitor to a different value.
- a tuning arrangement of the type defined in the opening paragraph is characterized in that in the last-mentioned circuit the padding capacitor is shunted by a coil, which compensates, at least partly, the capacitance of the padding capacitor within the tuning range of this circuit and in that the resonant frequency determined by the coil and the padding capacitor is located below the lowest tuning frequency of the relevant circuit.
- a preferred embodiment of a tuning arrangement according to the invention is characterized in that said circuit having the higher resonant frequency is the resonant circuit of the oscillator circuit and that the coil limits the tuning range of this circuit at the low frequency end.
- a further preferred embodiment of a tuning arrangement according to the invention is characterized in that the tuning range of the tuning arrangement includes at least the standardized television frequency band VHF I and the resonant frequency of the oscillator resonant circuit is an order of magnitude of 40 MHz above the resonant frequency of the RF-circuit, the padding capacitor having a capacitance of the order of magnitude of 120 pF and the coil having a value of the order of magnitude of 70 nH.
- FIG 1 shows a tuning arrangement according to the invention from which, for the sake of clarity, the measures for biasing the circuits have been omitted and in which coupling capacitors which have no signal function but have, for example, only for their object to block the tuning voltage, are denoted by C k .
- the tuning arrangement comprises, coupled one after the other in an aerial A: a broadband input network 1, a tunable RF-circuit 2, via a coupling filter LaCa a selective amplifier stage 3 which may comprise one or more tunable circuits, not shown, and a mixer stage 4.
- Oscillator signals are applied from an oscillator circuit 6 to the mixer stage 4 with for converting to a fixed intermediate frequency the RF-signal which is selected by the RF-circuit 2 and the selective amplifier stage 3 and applied to the mixer stage 5, which IF-signal is available at an output 5.
- the RF-circuit 2 comprises a parallel LC- resonant network L" L 2 , C, having a grounded inductance L, in the inductive branch, in parallel with which an inductance L 2 can be switched, using a switch S 1 which in practice is a switching diode, and having in the capacitive branch a variable capacitance diode C, whose anode is coupled to ground and whose cathode is coupled to the inductance L, via a coupling capacitor C A .
- a variable tuning voltage V tun is applied to this diode C 1 from a tuning voltage input V t .
- the oscillator 6 comprises an oscillator transistor T whose base is connected to ground via a coupling capacitor C K and whose collector is coupled to a resonant circuit C 2 , Cp, L 4 , L s , L e and also to the mixer stage 4 via a coupling capacitor C K .
- the resonant circuit C 2 , Cp, L 4 , L c is shown for alternating current in Figure 1A and comprises two parallel branches, one branch of which includes a grounded inductance L 4 in parallel with which (see Figure 1) an inductance L s can be arranged, also by means of a switch S 2 in the form of a switching diode, and whose other branch comprises a series arrangement of a variable capacitance diode C 2 and a grounded padding capacitor Cp.
- the padding capacitor Cp is shunted by a grounded coil L c , which will be described in the sequel.
- the junction between the diode C 2 and the padding capacitor Cp is coupled, for a regenerative feedback of the oscillator, via a coupling capacitor C K and a coupling resistor R K to the emitter of the oscillator transistor T.
- the cathode of the diode C 2 faces said junction, to which the same tuning voltage V tun is applied as to the cathode of the diode C 1 from the tuning voltage input V t via the coil L c .
- the tuning arrangement described so far, for coil L c excepted, corresponds to the above-mentioned known TV-tuning arrangement ELC 2006 and is suitable for tuning to a desired TV-signal in inter alia the low-VHF-band which in addition to the standardized VHF I-band (48.25 ⁇ 62.25 MHz) also includes the frequency range above this standardized VHF I-band to 105.25 MHz and, after closure of the switches S 1 and S 2 , for tuning to a desired TV-signal in the high VHF-band (112.25-294.25 MHz) in accordance with the CCIR system standard B.
- the frequency of the TV-signal selected by the RF-circuit 2 and the selective amplifier 3 is converted in the mixer stage 4 to a fixed intermediate frequency of 38.9 MHz and the tuning frequency of the oscillator resonant circuit is then predominantly located by a frequency value of the order of magnitude of 40 MHz above the tuning frequency of the RF-circuit 2.
- a variation of the tuning over both bands is effected by varying the tuning voltage V tun in each of these VHF-frequency bands over predominantly the same tuning voltage range (approximatley 1 to 28 V). This causes the capacitances of the two diodes C 1 and C 2 to vary in each of the two VHF-frequency bands, also through a mutually predominantly equal capacitance range (approximately from 40 to 3 pF). As is known, the diode capacitance then varies in a direction opposite to the direction of the tuning voltage and that of the tuning frequency.
- the diode in the circuit having the lower tuning frequency, i.e. C, in the RF-circuit 2 predominantly determines the circuit capacitance. This results in a certain length of the tuning frequency range and a certain variation in the tuning slope therein, which deviate from those of the oscillator circuit having the higher tuning frequency. A certain reduction in these deviations, more specifically for tuning the high VHF-frequency band, is obtained with the aid of the padding capacitor Cp, which reduces the relative variation of the circuit capacitance and consequently the tuning slope of the oscillator resonant circuit.
- the padding capacitor is chosen to have an ade- quantely high value to ensure acceptable tracking at the high frequency end of the tuning range (for example at the top of the high VHF-frequency band) then in practice it appeared that in the lower portion of the tuning range, more specifically in said low VHF-band, the tuning frequency of the oscillator resonant circuit gets undesirably close to the tuning frequency of the RF circuit, at a decreasing frequency.
- the padding capacitor Cp in the known tuning arrangement is given a lower value at the transition of tuning from the lowest tuning frequency (112.5 MHz) of the high VHF-band to the highest tuning frequency (105.25 MHz) of the low VHF-band, by arranging an additional circuit capacitance (not shown) in parallel therewith.
- this requires a switching diode (not shown).
- the switching current of a such a switching diode can hardly be prevented from flowing through the circuit and will consequently produce hum and/or other low-frequency noise voltages across the variable capacitance diode C 2 .
- This low-frequency noise voltage may be impermissibly large and may result in a disturbing frequency modulation of the oscillator signal.
- the padding capacitor Cp is chosen to have an adequately low value to ensure acceptable tracking in the low-VHF frequency band then, when tuning is effected in the high VHF frequency band the tuning frequency of the oscillator resonant circuit has been found to remove itself undesirably far from the tuning frequency of the RF circuit, at an increasing frequency.
- the choice of the value of the padding capacitor Cp is limited by the required mutual matching of the sizes of the tuning ranges of the two circuits.
- the padding capacitor Cp was chosen, as it was also in the prior art tuning arrangement, to have an adequately high value to provide satisfactory tracking at the high frequency end of the tuning range, that is to say in said high VHF frequency band and, at a decreasing tuning frequency, an increasing reduction occurs, in contrast with what occurs in the known tuning arrangement, on the apparent or the effective capacitance of the tuning capacitor Cp because of the effect of the coil L c .
- This coil L c is chosen such that the resonant frequency determined by the coil L c and the padding capacitor Cp decreases to below the lowest frequency in the tuning range of the oscillator resonant circuit.
- the reduction in the apparent capacitance of the padding capacitor Cp varies, as is known, predominantly in proportion to the square of the quotient of on the hand the tuning frequency of the oscillator resonant circuit and on the other hand to the last-mentioned resonant frequency determined by L c and Cp.
- variable capacitors C 1 and C 2 are constituted by variable capacitance diodes of the type BB909B, which have a variation in capacitance from 3 to 40 pF in a tuning voltage variation range from 28 to 1 V.
- Figures 2A to 2C illustrate by means of the curves hf 1 to hf 3 , respectively the shape of and the location of the overall frequency characteristic of the RF-circuit 2 and the selective amplifier as used in the tuning arrangement shown in Figure 1 at the respective tuning frequencies 105.25 MHz, 55.25 MHz and 48.25 MHz.
- Curves f, to f 3 illustrate the shape and the location of the frequency characteristic of the oscillator resonant circuit (not shown) without the coil L c
- curves f 1 ' to f3' illustrate the shape and the location of the frequency characteristic of the oscillator resonant circuit when it comprises the coil L c , as is shown in Figure 1, at the same respective tuning frequencies as mentioned above.
- the effect of the coil L c is so small as to be disregarded and, at an increasing frequency, is expressed in a growing increase of the resonant frequency of the oscillator resonant circuit.
- this achieves that the frequency spacing between the selected RF picture carrier and the oscillator frequency in the overall frequency range of the low VHF-band is substantially constantly 38.9 MHz.
- a decrease in the tuning frequency to below the lowest frequency (48.25 MHz) of the low VHF-band consequently requires such a high reduction in the tuning voltage V tun, that the lower limit of the control range of this tuning voltage V tun is quickly reached, so that tuning to an impermissible tuning'frequency is prevented.
Landscapes
- Channel Selection Circuits, Automatic Tuning Circuits (AREA)
- Inductance-Capacitance Distribution Constants And Capacitance-Resistance Oscillators (AREA)
- Superheterodyne Receivers (AREA)
- Transmitters (AREA)
- Semiconductor Lasers (AREA)
- Magnetic Resonance Imaging Apparatus (AREA)
Claims (3)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT85200507T ATE41841T1 (de) | 1984-04-12 | 1985-04-01 | Abstimmanordnung. |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
NL8401174A NL8401174A (nl) | 1984-04-12 | 1984-04-12 | Afsteminrichting. |
NL8401174 | 1984-04-12 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0160331A1 EP0160331A1 (de) | 1985-11-06 |
EP0160331B1 true EP0160331B1 (de) | 1989-03-29 |
Family
ID=19843797
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP85200507A Expired EP0160331B1 (de) | 1984-04-12 | 1985-04-01 | Abstimmanordnung |
Country Status (7)
Country | Link |
---|---|
US (1) | US4628540A (de) |
EP (1) | EP0160331B1 (de) |
JP (1) | JPS60230713A (de) |
AT (1) | ATE41841T1 (de) |
DE (1) | DE3569179D1 (de) |
ES (1) | ES8607644A1 (de) |
NL (1) | NL8401174A (de) |
Families Citing this family (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4837852A (en) * | 1985-06-17 | 1989-06-06 | Toko, Inc. | Electronic tuning circuit for AM receiver which is easy to effect tracking adjustment |
JPS6318711A (ja) * | 1986-07-10 | 1988-01-26 | Toko Inc | 電子同調受信機 |
US4996599A (en) * | 1989-04-14 | 1991-02-26 | Rca Licensing Corporation | Television tuner oscillator with three point tracking |
US5715528A (en) * | 1996-02-08 | 1998-02-03 | Ford Motor Company | Converting capacitance to inductance in a floating resonant |
JPH10173565A (ja) * | 1996-12-10 | 1998-06-26 | Toko Inc | Amラジオ受信機 |
JP2008141655A (ja) * | 2006-12-05 | 2008-06-19 | Alps Electric Co Ltd | 可変同調回路及びテレビジョンチューナ |
JP6213318B2 (ja) * | 2014-03-13 | 2017-10-18 | オムロン株式会社 | 電流共振型直流電圧変換器、制御用集積回路および電流共振型直流電圧変換方法 |
Family Cites Families (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
BE400555A (de) * | 1933-01-02 | |||
US3354397A (en) * | 1964-02-12 | 1967-11-21 | Standard Kollsman Ind Inc | Voltage variable diode capacitance tunable circuit for television apparatus |
GB1121439A (en) * | 1965-08-03 | 1968-07-24 | Int Standard Electric Corp | Electronic tunable oscillator circuit |
DE1296226C2 (de) * | 1967-12-09 | 1978-03-16 | Philips" Patentverwaltung GmbH, 2000 Hamburg | Abstimm-schaltungsanordnung mit einer schaltdiode |
US3582791A (en) * | 1968-12-11 | 1971-06-01 | Bendix Corp | Antenna coupling and tuning circuit |
DE2137408A1 (de) * | 1970-08-07 | 1972-02-24 | Ducati Elettrotecnica Spa | Abgleichsschaltkreis in Abstimm vorrichtungen mit Drehkondensator |
JPS4955209A (de) * | 1972-09-29 | 1974-05-29 | ||
US4247953A (en) * | 1977-07-01 | 1981-01-27 | Hitachi, Ltd. | Tunable high-frequency input circuit |
CA1180139A (en) * | 1979-09-14 | 1984-12-27 | Isao Fujimoto | Tuner apparatus |
-
1984
- 1984-04-12 NL NL8401174A patent/NL8401174A/nl not_active Application Discontinuation
-
1985
- 1985-03-25 US US06/715,570 patent/US4628540A/en not_active Expired - Fee Related
- 1985-04-01 EP EP85200507A patent/EP0160331B1/de not_active Expired
- 1985-04-01 AT AT85200507T patent/ATE41841T1/de not_active IP Right Cessation
- 1985-04-01 DE DE8585200507T patent/DE3569179D1/de not_active Expired
- 1985-04-09 JP JP60073629A patent/JPS60230713A/ja active Granted
- 1985-04-09 ES ES542052A patent/ES8607644A1/es not_active Expired
Also Published As
Publication number | Publication date |
---|---|
DE3569179D1 (en) | 1989-05-03 |
ATE41841T1 (de) | 1989-04-15 |
ES8607644A1 (es) | 1986-05-16 |
NL8401174A (nl) | 1985-11-01 |
ES542052A0 (es) | 1986-05-16 |
JPH0451089B2 (de) | 1992-08-18 |
JPS60230713A (ja) | 1985-11-16 |
US4628540A (en) | 1986-12-09 |
EP0160331A1 (de) | 1985-11-06 |
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